In light of increasingly stringent regulations, reduction of volatile organic compounds (VOC) emissions from paint and other coatings has become a key concern of the coatings industry. Powder or solid coatings, water-based systems, and low solvent/high solids formulations have each been utilized as potential low-VOC alternatives, but each of these systems also has practical performance and economic drawbacks. For example, powder coating emits nearly no VOCs, but, as its application requires heating the substrate, such systems cannot necessarily be universally applied. Water-based systems, such as latexes, have also been used as low VOC coatings, but typically require the presence of a relatively high VOC solvent in order to provide a final coating exhibiting acceptable chemical and thermal resistance. In addition, most low solvent/high solids coating formulations require use of low molecular weight polymeric materials and, consequently, must be cross-linked via application of heat or UV light in order to achieve an acceptable finish. As such post-treatments are not always feasible, such coatings have limited application.
To remedy this problem, a few “self-curing” coatings have been developed that utilize an auto-oxidizing polymer, such as those containing the monomer Acetoacetoxyethyl methacrylate (AAEM), which cross-links in the absence of any additional treatment. Unfortunately, AAEM-based coatings are hydrolytically labile and may degrade under hydrolyzing conditions. Such degradation can be minimized with addition of one or more additives, such as ammonia, but the presence of these additives often adversely impacts the color and/or odor of the final coating.
Thus, a need exists for a hydrolytically stable polymer suitable for use in a low VOC, self-curing coating composition. Desirably, the polymer and coatings produced therefrom would be economically viable and could easily be implemented on a large production scale for a minimal cost.